One common theme could be the struggle between different beliefs or ideologies, given the nature of 'faith seed'. Another might be the development of an unlikely relationship between the deputy and the elements related to 'faith seed'.
I'm not sure specifically which 'faith seed x deputy' fanfictions are available. You could try searching on popular fanfiction websites like Archive of Our Own. There might be a variety of stories there with different plotlines and interpretations.
A 'joseph x caesar fanfic' could potentially explore the relationship between Joseph and Caesar in unique ways. It might focus on their friendship, adventures they have together, or how they support each other in a fictional setting. For example, it could show how their different personalities, Joseph being perhaps more brash and Caesar more refined, interact and create interesting story dynamics.
There are also themes of sacrifice. Maybe one of them has to sacrifice something for the other. It could be a personal goal, a possession, or even a relationship with someone else. This theme can create a lot of drama and emotional tension in the fanfic. Also, the theme of acceptance is common. They accept each other's flaws and differences, which strengthens their bond.
Another theme is the idea of finding acceptance. Aesop, with his rather unique occupation, may find acceptance in Joseph's company. Many fanfictions focus on how Joseph accepts Aesop for who he is and helps him break out of his shell a bit. It's about two characters from different worlds coming together and finding common ground.
One common theme is loyalty. Joseph and Caesar are likely to be shown as being loyal to each other in the face of danger. Another theme could be growth. They might start off as rivals but grow to be friends as they face challenges together.
Adventure is also quite common. Since they are often in action - packed situations in the original story, fanfics continue this trend. They face new enemies and obstacles together. Another theme could be loyalty. They are loyal to each other no matter what, and this is emphasized in many fanfics. It can be shown in different ways, like standing up for one another in tough situations or believing in each other when others don't.
There is a fanfic called 'Joseph's Discovery of Aesop'. In this, Joseph is initially intrigued by Aesop's mysterious aura. As the story unfolds, he tries to break through Aesop's shell. It has some really sweet moments where Joseph shows Aesop the beauty of life outside his usual routines, like taking him to see beautiful sunsets in the manor's garden.
Yes, there are quite a few. You can start by looking on fanfiction websites like Archive of Our Own. Just search for 'Joseph x Avdol' and you'll find a variety of stories with different themes and writing styles.